Split roof for a metallurgical furnace

ABSTRACT

An apparatus is disclosed for a split spray-cooled roof for a tilting metallurgical furnace. The split spray-cooled roof has a center, a first hollow metal roof section and a second hollow metal roof section. The first and second hollow roof sections are attached together along a prescription split line. The prescription split line having a first split line and a second split line, wherein the first split line is not aligned with the second split line and wherein the first and second split line are not aligned with the center.

BACKGROUND OF THE DISCLOSURE Field of the Disclosure

Embodiments of the present disclosure relates generally to aspray-cooled roof for a metallurgical furnace, particularly an electricarc furnace that heats charged metal by means of an electric arc via agraphite electrode.

Description of the Related Art

Metallurgical furnaces (e.g., an electric arc furnace or a ladlemetallurgical furnace) are used in the processing of molten metalmaterials. The electric arc furnace heats charged metal in the furnaceby means of an electric arc from a graphite electrode. The electriccurrent from the electrode passes through the charged metal materialforming a molten bath of the metal materials. The furnaces house themolten materials during the processing of the molten materials formingmolten steel and slag (a stony waste material).

A metallurgical furnace has a number of components, including a roofthat is retractable, a hearth that is lined with refractory brick, and asidewall that sits on top of the hearth. The metallurgical furnacetypically rests on a tilting platform to enable the furnace to tiltabout an axis. During the processing of molten materials, the furnacetilts in a first direction to remove slag through a first opening in thefurnace referred to as the slag door. Tilting the furnace in the firstdirection is commonly referred to as “tilting to slag.” The furnace mustalso tilt in a second direction during the processing of moltenmaterials to remove liquid steel via a tap spout. Tilting the furnace inthe second direction is commonly referred to as “tilting to tap.” Thesecond direction is generally in a direction substantially opposite thefirst direction.

Because of the extreme heat loads generated during the processing ofmolten materials within the metallurgical furnace, various types ofcooling methods are used to regulate the temperature of, for example,the roof and sidewall of the furnace. One cooling method, referred to asnon-pressurized spray-cooling, sprays a fluid-based coolant (e.g.,water) against an external surface of plate. The plate may be a part ofa roof of the furnace or a part of a sidewall of the furnace. For thiscooling method, the fluid-based coolant is sprayed from a fluiddistribution outlet at atmospheric pressure. As the fluid-based coolantcontacts the external surface of the plate, the plate is relieved ofheat transferred to the plate from the molten materials within thefurnace, thus regulating the temperature of the plate. An evacuationsystem is used to continually remove spent coolant (i.e., coolant thathas contacted the external surface of the plate) from the plate.

The intense heat and harsh environment, along with the complex coolingand draining system for the roof of the furnace, require periodicmaintenance and refurbishment of the roof for the electric arc furnace.The roof is so designed to be removable for such operations. However,the size and complexity of the spray-cooled roof makes it difficult andexpensive when it is time to remove, repair and replace the spray-cooledroof. The spray-cooled roof typically requires special accommodationsand equipment for moving and shipping. The cost of these accommodationsand equipment coupled with the assembly and disassembly time can becomeexpensive. Costs related to moving or shipping the spray-cooled roof formaintenance are attributable to the costs associated with the assemblyand disassembly of the spray-cooled roofs due to the large size andcomplexity of the spray-cooled roof.

Therefore, there is a need for an improved spray-cooled roof.

SUMMARY

A split spray-cooled roof for a tilting metallurgical furnace isdescribed herein. The split spray-cooled roof has a first hollow metalroof section and a second hollow metal roof section. The first andsecond hollow roof sections mating along a prescription split line andbounding at least a portion of a central opening of the roof. Aninterconnecting cross-over drain is coupled to the first and secondhollow roof sections. The interconnecting cross-over drains allowgravitational fluid passage from an enclosed space of one of the hollowmetal roof sections to an enclosed space in the adjacent hollow metalroof section when the roof is tilted.

In another example, a split spray-cooled roof for a tiltingmetallurgical furnace is described herein. The split spray-cooled roofhas a center, a first hollow metal roof section and a second hollowmetal roof section. The first and second hollow roof sections areattached together along a prescription split line. The prescriptionsplit line has a first split line and a second split line, wherein thefirst split line is not aligned with the second split line, and whereinthe first and second split lines are not radially aligned with thecenter.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the way the above recited features of the present disclosure canbe understood in detail, a more particular description of thedisclosure, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this disclosure and are therefore not to beconsidered limiting of its scope, for the disclosure may admit to otherequally effective embodiments.

FIG. 1 illustrates an elevational side view of a metallurgical furnacehaving a spray-cooled roof.

FIG. 2 illustrates a top plan view of the spray-cooled roof assembly ofFIG. 1.

FIG. 3 illustrates an exploded orthogonal view showing two hollow metalroof sections of the spray-cooled roof assembly of FIG. 1.

FIG. 4 illustrates a cross-section detail for a connection engagingadjacent hollow metal roof sections of the spray-cooled roof shown inFIG. 3

FIG. 5 illustrates an orthogonal view for one of the hollow metal roofsections of FIG. 3.

FIG. 6 illustrates the difference for the diameter length of the hollowmetal roof sections compared to the diameter of the spray-cooled roofassembly.

DETAILED DESCRIPTION

The present invention is directed to a metallurgical electric arcfurnace having a split spray-cooled roof comprising at least two,separate hollow metal roof sections detachably interconnected to beseparately removable, shipped and installed together. A spray coolingsystem is employed within each of the hollow metal roof sections toprevent overheating of the roof's inner metal base member.

Some embodiments include interconnecting cross-over drains that providea gravity fed fluid passage from an enclosed space of one hollow metalroof sections to another when the roof is tilted. The cross-over drainsadvantageously make certain that spent cooling fluid is directed to adrain of the roof even when the roof is tilted.

In some embodiments, the first and second hollow roof sections areattached together along a prescription split line. The prescriptionsplit line has a first split line and a second split line, wherein thefirst split line is not aligned with the second split line, and whereinthe first and second split lines are not radially aligned with thecenter. The non-radial alignment of the first and second split linesallows the disassembled roof to be smaller in size as separate pieces.Stated differently, the non-radial alignment of the first and secondsplit lines results in the first and second hollow roof sections havinga smaller geometrical size relative to a conventional roof of the samediameter. Thus, the non-radial alignment of the first and second splitlines enable the roof to be more easily put into service at lessexpense, while also enabling larger diameter roofs to be installed inlocations having access constraints that would have preventedconventional roofs, assembled by welding, from being utilized.

Other embodiments include both interconnecting cross-over drains andnon-radial alignment of the first and second split lines. Generally,each hollow metal roof section is detachably interconnected to adjacenthollow metal roof sections. The interconnection permits close engagementof each hollow metal roof section with each adjacent hollow metal roofsection via a bolted, pinned, or other suitable connection which allowsfor thermal expansion of the spray-cooled roof without compromisingfluid tightness for the spray-cooled system. A radial split line chamferis provided along a lowermost edge of the interconnection of the hollowmetal roof sections to redistribute and reduce stresses in the thermallystressed areas of the spray-cooled roof. The outermost portions of thehollow metal roof sections define an outer, circular periphery of theroof which is supported by the underlying upper shell of the body of themetallurgical electric arc furnace. The hollow metal roof sections arearranged to be closely adjacent and define an inner opening whichprovides vertical access through the spray-cooled roof for at least onegraphite electrode to pass therethrough into the metallurgical electricarc furnace there below. The coolant supply header conduit for eachhollow metal roof section is detachably interconnected with a commonsource of coolant by way of an outboard coolant supply for thespray-cooled system. Coolant drain outlets are provided to receive spentcoolant from inside each hollow metal roof section. Peripheralinterconnected cross-over drains are detachable and provide drainagefrom one hollow metal roof section into an adjacent hollow metal roofsection for maintaining operative evacuation of coolant from the splitspray-cooled roof. A peripheral detachably interconnected extensionconnects disjointed evacuation drain sections from the hollow metal roofsections to form a continuous unitary circumferential drain channel.Peripheral interconnected cooling water supply headers for the spraycooling system are detachable and combine to form a unitary header forthe coolant supply.

FIG. 1 illustrates an elevational side view of a metallurgical furnace190 having a spray-cooled roof 100. The metallurgical furnace 190 has abody 192. The body 192 has a hearth 101 that is lined with refractorybrick 105, and a sidewall 107 that sits on top of the hearth 101. Thesidewall 107 has a top 159. The spray-cooled roof 100 is moveablydisposed on the top 159 of the sidewall 107. The metallurgical furnace190 has an interior volume 111. The interior volume 111 of themetallurgical furnace 190 enclosed by the spray-cooled roof 100 and thebody 192. The interior volume 111 may be loaded or charged with material103, e.g., metal, scrap metal, or other meltable material, which is tobe melted within the metallurgical furnace 190.

The metallurgical furnace 190, including the body 192 and thespray-cooled roof 100, is rotatable along a tilt axis 180 about whichthe metallurgical furnace 190 can tilt. The metallurgical furnace 190may be tilted in a first direction about the tilt axis 180 toward theslag door (not shown) multiple times during a single batch meltingprocess, sometimes referred to as a “heat”, to remove slag. Similarly,the metallurgical furnace 190 may be tilted in a second direction aboutthe tilt axis 180 towards a tap spout (not shown) multiple times duringa single batch melting process including one final time to remove themolten material 103.

Roof lift members 102 may be attached at a first end to the spray-cooledroof 100. The roof lift members 102 may by chains, cables, ridgedsupports, or other suitable mechanisms for supporting the spray-cooledroof 100. The roof lift members 102 may be attached at a second end toone or more mast arms 104. The mast arms 104 extend horizontally andspread outward from a mast support 108. The mast support 108 may besupported by a mast post 110. A coupling 109 may attach the mast post110 to the mast support 108. The mast support 108 may rotate about thecoupling 109 and the mast post 110. Alternately, the mast post 110 mayrotate with the mast support 108 for moving the roof lift members 102.In yet other examples, roof lift members 102 may be aerially supportedto move the spray-cooled roof 100. In one embodiment, the spray-cooledroof 100 is configured to swing or lift away from the sidewall 107. Thespray-cooled roof 100 is lifted away from the sidewall 107 to expose theinterior volume 111 of the metallurgical furnace 190 through a top 159of the sidewall 107 for loading material therein.

The spray-cooled roof 100 may be circular in shape when viewed from atop plan view, such as shown in FIG. 2. A central opening 124 may beformed through the spray-cooled roof 100. Electrodes 120 extend throughthe central opening 124 from a position above the spray-cooled roof 100into the interior volume 111. During operation of the metallurgicalfurnace 190, the electrodes 120 are lowered through the central opening124 into the interior volume 111 of the metallurgical furnace 190 toprovide electric arc-generated heat to melt the material 103.

The spray-cooled roof 100 may further include an exhaust port to permitremoval of fumes generated within the interior volume 111 of themetallurgical furnace 190 during operation.

FIG. 2 illustrates a top plan view of the spray-cooled roof 100 ofFIG. 1. A prescription split line 202 separates the spray-cooled roof100 into adjoining mating hollow metal roof sections. Although twohollow metal roof sections 203, 201 are illustrated in FIG. 2, theprescription split line(s) may be utilized to segment the spray-cooledroof 100 into any reasonable number of hollow metal roof sections. Thespray-cooled roof 100 has an outer wall 219 and an inner wall 218. Theinner wall 218 bounds the central opening 124 which is locatedconcentric to a center (e.g., the centerline) 299 of the spray-cooledroof 100. The central opening 124 may separate the prescription splitline 202 into a first split line 271 and a second split line 272. Thespray-cooled roof 100 may have an upwardly sloping shape, for example afrustoconical or torispherical shape, and is disposed over themetallurgical furnace 190 to enclose the interior volume 111.Alternatively, the spray-cooled roof 100 may have other shapes.

The first split line 271 and the second split line 272 extend from theouter wall 219 to an inner wall 218. A first imaginary line 277extending through an outer end of the first split line 271 and an outerend of the second split line 272 may traverse through the center 299. Inthe example of FIG. 2, the first imaginary line 277 extends through thecenter 299, but alternatively, the first imaginary line 277 may beoffset from the center 299. Similarly, a second imaginary line 276extending through an inner end of the first split line 271 and an innerend of the second split line 272 may traverse through the center 299.However, the first imaginary line 277 is not linearly aligned with thesecond imaginary line 276. Similarly, the first split line 271 is notaligned (i.e., is not collinear) with the second split line 272. In afirst example, neither the first split line 271 nor the second splitline 272 is radially aligned with the center 299. In a second examplethat may be in addition or alternative to the first example, the firstsplit line 271 nor the second split line 272 is aligned with the firstimaginary line 277. In a third example that may be in addition oralternative to the first example and/or the second example, neither thefirst split line 271 nor the second split line 272 is aligned with thesecond imaginary line 276. In the example illustrated in FIG. 2, thefirst and second split lines 271, 272 may be formed at an angle 275 tothe first imaginary line 277. The hollow metal roof sections 203, 201are connected to one another along the prescription split line 202. Thehollow metal roof sections 203, 201 may be attached or detached fromeach other. Although, only two hollow metal roof sections 203, 201 areshown, the spray-cooled roof 100 may have a plurality of hollow metalroof sections, such as three or more. The separate hollow metal roofsections 203, 201 are attached to any adjacent separate hollow metalroof sections to form the spray-cooled roof 100. In this manner thermalexpansion of the adjoining hollow metal roof sections 203, 201 does notstress the joints between the hollow metal roof sections 203, 201 or theconnections for the coolant and drain system enabling the coolant anddrain systems to remain free from leakage.

The mating hollow metal roof sections 201, 203 may be attached along theprescription split line 202 using fasteners, pins, welds, clamps orattached by any suitable joining technique. In one embodiment, thehollow metal roof sections 201, 203 are detachably interconnected withbolts in a manner such that the sections 201, 203 may be easilyseparated and reassembled together. Here, two detachably interconnectedhollow metal roof sections 201, 203 are separated along the prescriptionsplit line 202. It should be appreciated that introducing additionalhollow metal roof sections would introduce additional split lines. Forexample, a spray-cooled roof 100 formed from three hollow metal roofsections would have a first, second and third split line between eachadjoining hollow metal roof sections.

The spray-cooled roof 100 has a spray cooling system 550 that isdetailed further below with reference to FIGS. 4 and 5. Coolant supply130 provides coolant to the spray cooling system 550 interfaced with thespray-cooled roof 100. The coolant, such as water or other suitablefluid, is provided internally to each hollow metal roof section 201,203. Coolant supply connections 209 and 210 provide fluid connectionbetween the coolant supply 130 and the spray cooling system 550 in eachof the hollow metal roof sections 201, 203. The coolant is sprayedwithin the hollow metal roof sections 201, 203 of the split spray-cooledroof to maintain the inner metal base member of the spray-cooled roofbelow a maximum operating temperature.

The split spray-cooled roof includes detachable interconnectingcross-over drains that couple the hollow interiors (also referred to as“enclosed space”) of the adjacent hollow metal roof sections across theprescription split line 202. For example, as shown in FIGS. 2 and 5,interconnecting cross-over drains 211, 212 provide a fluid passagebetween the hollow interior of the hollow metal roof sections 201 andthe hollow interior of the hollow metal roof sections 203. Theperipheral detachably interconnecting cross-over drains 211, 212 areconnected to the hollow metal roof sections 201, 203 at the lowermostportion of hollow metal roof sections 201, 203 so that adjacent sectionsof the spray-cooled roof 100 to realize complete evacuation of spentcooling water from the hollow interior of one roof section to the hollowinterior of the adjacent roof section. In one embodiment, a portion ofeach interconnecting cross-over drains 211, 212 may be coupled to eachhollow metal roof section 201, 203, with the portion of the drains 211,212 fastened together to form the passages between the hollow interiors.In other embodiments, the interconnecting cross-over drains 211, 212 maybe single or multiple pipes having ends coupled to each of the hollowmetal roof section 201, 203 to form the passages between the hollowinteriors. Beneficially, the interconnecting cross-over drains 211, 212provide a gravity fed fluid passage from the enclosed hollow interior ofone hollow metal roof section to the enclosed hollow interior of theadjacent hollow metal roof section, even when the roof is tilted fromhorizontal during tilting to slag and tilting to tap operations. Thecross-over drains advantageously make certain that spent cooling fluidwithin the hollow interiors is directed to a drain of the roof even whenthe roof is tilted.

An external evacuation drain 213 is provided along the outer wall 219 ofeach hollow metal roof section 201, 203. A peripheral detachablyinterconnected extension 216 connects the evacuation drain 213 alongeach hollow metal roof section 201, 203 to form a continuous unitarycircumferential drain to dedicated outlets 150, 152 exiting the one ofthe hollow metal roof section, such as section 203. In one embodiment, aportion of each interconnected extension 216 may be coupled to eachportion of the evacuation drain 213 associated with one of hollow metalroof sections 201, 203, with the portion of the interconnected extension216 fastened together to form the passages between each portion of theevacuation drain 213. In other embodiments, the interconnected extension216 may be formed from single or multiple pipes having ends coupled toeach portion of the disjointed evacuation drain 213.

FIG. 3 illustrates an exploded orthogonal view showing two hollow metalroof sections 203, 201 of the spray-cooled roof 100 of FIG. 1. FIG. 4illustrates a cross-section detail of a connection engaging adjacenthollow metal roof sections 203, 201 of the spray-cooled roof 100 alongthe prescription split line 202 shown in FIG. 3. FIG. 5 illustrates anorthogonal view for one of the hollow metal roof sections 203 of FIG. 3.Simultaneously referring to FIGS. 3 and 5, each of the hollow metal roofsections 203, 201 are provided with a downwardly opening metal supportmember 304 which seats with the circular peripheral top 159 of theunderlying body 192 of the metallurgical furnace 190.

The interconnecting cross-over drains 211, 212 and the conventionalspray-cooled internal or external evacuation drain 213 too are showndetached in the elevational view. The peripheral detachablyinterconnected extension 216 connects disjointed evacuation drain 213 toform a continuous unitary circumferential drain coupled to dedicatedoutlets 150, 152 exiting from the hollow metal roof section 203. Aparting wall 314 separating the detachably interconnected roof sectionsserves to isolate one roof section from the other so thatinterconnectivity can be maintained with a fastening connection 405along the prescription split line 202 discussed further below withrespect to FIG. 4 without leakage of spent fluid from within theinterior of the hollow roof sections. Once the hollow metal roofsections 201, 203 are mated together along the prescription split line202, the parting walls 314, drains 211, 212, 213, coolant supplyconnections 209, 210 and interconnected extension 216 all may beassembled together for forming the spray-cooled roof 100.

Turning now to FIG. 4, each hollow metal roof section 201, 203 isprovided with connections 405 across the parting walls 314. In oneembodiment, the connections 405 utilize bolts and nuts to securely holdthe hollow metal roof sections 203, 201 together. Two hollow metal roofsections 203, 201 have an inner metal base member 406 and outer metalcovering member 407. Each hollow metal roof section 201, 203 removablyengages with the adjacent hollow metal roof section along the partingwalls 314. An enclosed space 430 (also referred to as “hollow interior”)is defined within each hollow metal roof section 201, 203 between anouter metal covering member 407, an inner metal base member 406 and theparting wall 314. The inner metal base member 406 is a plate having anexternal surface directly facing the interior volume 111 of themetallurgical furnace 190 in which the material 103 is processed. Aradial split line chamfer 415 is provided along a lowermost edge of theinner metal base member 406. The radial split line chamfer 415redistributes and reduces thermal stress in the area where the twohollow metal roof sections 203, 201 are joined. Additionally, spacers419 and 420 may be utilized to separate the detachably interconnectedhollow metal roof sections 203, 201 to allow for thermal expansion andlessening of associated expansion and contraction stresses.

Referring now to FIG. 5, the hollow metal roof section 203 is shown withthe parting wall 314 removed. The hollow metal roof section 201 issimilarly constructed. The hollow metal roof section 203 comprises anupwardly sloping inner metal base member 406 shaped to form apredetermined portion of the spray-cooled roof 100. The outer metalcovering member 407 may additionally be shaped to form a predeterminedportion of the spray-cooled roof 100. The outer metal covering member407 is spaced from and opposite and quasi-parallel to the inner metalbase member 406.

A liquid coolant supply header conduit 508 of the spray cooling system550 affixed at an entrance to the hollow metal roof section 203 andextending around the inner metal base member 406 is provided. Peripheraldetachably interconnecting coolant supply connections 209, 210 nearerthe top of hollow metal roof section 203 communicate with the liquidcoolant supply header conduits 508 disposed in adjoining hollow metalroof sections 201, 203 so that the cooling system 550 of the entire roof100 may be supplied coolant from a single supply source. A liquidcoolant supply conduit (not shown) for supplying liquid directly to eachremovable hollow metal roof section 201, 203 from a liquid coolantsupply source is located outboard of the spray-cooled roof 100 and isconnected to the liquid coolant supply header conduit 508.

The spray cooling system 550 is utilized to prevent excessive heatbuildup in the inner metal base member 406 of the spray-cooled roof 100.As mentioned above, the spray cooling system 550 is attached to thecoolant supply header conduit 508. The spray cooling system 550 isdisposed in the enclosed space 430 of each hollow metal roof section203. The spray cooling system 550 utilizes a fluid based coolant, suchas water or some other suitable liquid. The coolant supply headerconduit 508 is attached to a coolant supply system, such as coolantsupply connections 209, 210. The spray cooling system 550 maintains atemperature profile for the hollow metal roof section 203 by sprayingcoolant onto the upwardly sloping inner metal base member 406 exposed tothe interior volume 111 of the metallurgical furnace 190. The coolant issprayed inside the enclosed space 430 to maintain the temperature of theinner metal base member of the spray-cooled roof 100 at a desirablelevel.

In the embodiment illustrated in FIG. 4, the spray cooling system 550includes the liquid coolant supply header conduit 508, plurality ofbranch conduits 552 and fluid distribution outlets 554. The plurality ofbranch conduits 552 are fluidly coupled to the supply header conduit 508and extend therefrom within the enclosed space 430. The fluiddistribution outlets 554 are disposed on the distal ends of each branchconduit 552 within the enclosed space 430. Coolant flows into the liquidcoolant supply header conduit 508, through the branch conduits 552, outthe fluid distribution outlets 554, into the enclosed space 430, andonto the upwardly sloping inner metal base member 406 for cooling thehollow metal roof section 203.

An evacuation system 560 collects and removes the sprayed (i.e., spent)coolant from the enclosed space 430 of the hollow metal roof section203. The evacuation system 560 has one or more outer liquid drainopenings 524 located at the lowermost portion of the enclosed space 430.The outer liquid drain openings 524 collect the coolant sprayed in theenclosed space 430 by the spray cooling system 550 and empties into theevacuation drain 213 for removal, passing though the interconnectingcross-over drains 211, 212 as need in response to the spray-cooled roof100 being tilted from horizontal. Additionally, as shown in FIGS. 2 and5, the location of the cross-over drains 211, 212 is immediatelyproximate the parting walls 314. The location of the cross-over drains211, 212 immediately proximate the parting walls 314 allows spentcoolant flowing against the parting walls 314 when the spray cooled roof100 is in a tilted orientation to be routed directly into the cross-overdrains 211, 212 coupled to the higher of the hollow metal roof sections201, 203, and through the cross-over drains 211, 212 into the lower ofthe hollow metal roof sections 201, 203, thus ensuring that the spentcoolant will always be allowed to run by gravity to one of the outerliquid drain openings 524 so that the venturi pumps utilized to emptythe external evacuation drain 213 will remain functioning to drain thespray-cooled roof 100 regardless of the tilt inclination of thespray-cooled roof 100.

Returning to FIG. 3, lifting lugs 318 are attached to each of the hollowmetal roof sections 203, 201. The lifting lugs 318 provide attachmentpoints for an overhead crane, lift or other device to remove and installthe hollow metal roof sections 203, 201 from the spray-cooled roof 100.Additionally, the lifting lugs 318 serve to provide lift points forinstalling and removing the spray-cooled roof 100 from the metallurgicalfurnace 190. By way of example, one hollow metal roof section 203 ispositioned adjacent a second hollow metal roof section 201 by theoverhead crane or other device as shown in FIG. 3 and the overhead cranecan be detached and removed. The remaining hollow metal roof sections,when more than two roof sections are utilized, are similarly attached toeach other with fasteners. Thus, the hollow metal roof sections 201, 203can be individually and separately removed, e.g., for inspection,maintenance, or replacement.

Some additional advantages of the spray-cooled roof 100 are discussed inconjunction with FIG. 6. FIG. 6 illustrates the difference for a firstlength 610 of the hollow metal roof section 201 and a second length 620of the hollow metal roof section 203 compared to a diameter 699 of thespray-cooled roof 100 achieved as a result of the misaligned split lines271, 272 forming the prescription split line 202. The split line havingtwo sections, not aligned and not passing radially through the center ofthe roof, has two roles. First, splitting the roof along the splitline(s) enables shipping of two or more complete compatible roofsections requiring only mechanical assembly along the prescription splitline. This permits assembly on or off furnace and replacement of asingle section versus the whole roof. Shipping permits have typicallyrequired conventional spray-cooled roofs to be shipped in two sectionswhich had to be welded together upon receipt. Assembly of the roofsections by welding is expensive and time consuming. The mechanicalassembly saves multiple weeks of assembly time when assembling the partswithout expensive time consuming welding. Maintenance can be performedon the whole roof while requiring handling of only half the size piecesof the roof during the on-site maintenance process. Without having tocut the roof apart to ship it out for maintenance, the splitspray-cooled roof permits easy and quick removal of the assemblyattachments for shipping the sections out for maintenance similar to howthe spray-cooled roof sections were shipped in.

Second, the prescription split line, having two sections, not alignedand not passing radially through the center of the roof, intentionallyavoids co-alignment with the tap-to-slag centerline. All of which areoperationally busy locations around the roof circumference. The“prescribed” split line does not trap water anywhere in either of theroof sections when the furnace is tilted to tap or slag. The split lineis prescribed to still be near to the roof centerline between tap andslag since spent cooling water logically collects there when the furnaceis tilted. The coolant in the spray-cooled roof 100 is allowed to drainin each hollow metal roof section 201, 203 when the spray-cooled roof100 is tilted with the metallurgical furnace 190 in either direction(left or right) along the tilt axis 180 for slag removal or metalpouring. A first midpoint 628 along the interior wall is substantiallyorthogonal to the tilt axis. A second midpoint 618 along the interiorwall is substantially orthogonal to the tilt axis. Thus, tilting thespray-cooled roof 100 along the tilt axis 180 to the right will causecoolant within either hollow metal roof sections 201, 203 to flow bygravity to a drain on the outer wall 219 near a first endpoint 616.Similarly tilting the spray-cooled roof 100 along the tilt axis 180 tothe left will cause coolant within either hollow metal roof sections201, 203 to flow by gravity to a drain on the outer wall 219 near asecond endpoint 626. Accordingly, coolant does not become entrapped nearthe inner wall 218 and can escape the area near the inner wall 218 bygravity. Thus, the location of prescription split line 202 provides forbetter gravity feed coolant drainage in the spray-cooled roof 100 whenthe metallurgical furnace 190 is tilted.

Advantageously, the split design for the spray-cooled roof provides foreasy break down and assembly of the hollow metal roof sections withminimal connections for the coolant system and drainage. The hollowmetal roof sections are advantageously configured to provide gravitydrainage when assembled into the spray-cooled roof regardless of thetilt position of the furnace. The split line between the assembledhollow metal roof sections permits thermal expansion of the spray-cooledroof to occur without compromising the integrity of the coolant systemor creating undue stress on the spray-cooled roof itself. The breakdownof the spray-cooled roof into the hollow metal roof sections allow foreasy transport and handling while minimizing assembly and disassemblytime thus providing a more cost effective solution.

While the foregoing is directed to embodiments of the presentdisclosure, other and further embodiments may be devised withoutdeparting from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

What is claimed is:
 1. A split spray-cooled roof for a metallurgicalfurnace, the split spray-cooled roof comprising: a first hollow metalroof section; a second hollow metal roof section mating with the firsthollow metal roof section to bound at least a portion of a centralopening of the roof; and wherein the first and second hollow roofsections are attached together along a prescription split line passingthrough the central opening, the prescription split line comprising: afirst split line; and a second split line, wherein the first split lineis not aligned with the second split line, and wherein the first andsecond split line are not radially aligned with a center.
 2. The splitspray-cooled roof of claim 1 wherein the first and second hollow metalroof sections comprise: an upwardly sloping inner metal base memberforming a pre-determined portion of the roof; an outer metal coveringmember spaced from and in register with said inner metal base member;and an enclosed space defined between the inner metal base member andthe metal covering member.
 3. The split spray-cooled roof of claim 2wherein the enclosed space comprises: a coolant supply header conduitattached to fluid outlets populated throughout; a lower most portion; atleast one outer liquid drain opening being located at a lowermostportion of the enclosed space for spent coolant evacuation.
 4. The splitspray-cooled roof of claim 3 further comprising: an interconnectingcross-over drain fluidly coupling the enclosed space of the first metalroof section to the enclosed space of the adjacent second hollow metalroof section.
 5. The split spray-cooled roof of claim 3 wherein theliquid coolant supply header conduit disposed in the enclosed space ofthe first metal roof section is connected to the enclosed space of theadjacent second hollow metal roof section though a connection exteriorto the roof.
 6. The split spray-cooled roof of claim 3 furthercomprising: a first portion of an evacuation drain coupled to the firsthollow metal roof section; a second portion of the evacuation draincoupled to the second hollow metal roof section, and wherein the firstand second portions are detachably coupled by an interconnectedextension.
 7. The split spray-cooled roof of claim 1 further comprising:a connector removably fastening each hollow metal segment with eachadjacent hollow metal roof section.
 8. The split spray-cooled roof ofclaim 7 further comprising: spacers disposed between the second hollowmetal roof sections.
 9. The split spray-cooled roof of claim 1 furthercomprising: spacers disposed between adjacent walls of the first andsecond hollow metal roof sections.
 10. The split spray-cooled roof ofclaim 1 further comprising: radial split line chamfers disposed along alowermost edge of adjacent walls of the first and second hollow metalroof sections.
 11. A split spray-cooled roof for a metallurgicalfurnace, the split spray-cooled roof comprising: a first hollow metalroof section; a second hollow metal roof section attached to the firsthollow roof section along a prescription split line, wherein theprescription split line comprises: a first split line; and a secondsplit line, wherein the first split line is not aligned with the secondsplit line, and wherein the first and second split line are not radiallyaligned with a center of the central opening; and a firstinterconnecting cross-over drain coupling to an enclosed space of thefirst hollow metal roof section to an enclosed space of the secondhollow metal roof section in an orientation that allows gravitationalfluid passage between the enclosed spaces in response to the roof beingin a tilted orientation.
 12. The split spray-cooled roof of claim 11further comprising: a spray cooling system having water distributionoutlets disposed in the enclosed spaces of the first and second hollowroof sections.
 13. The split spray-cooled roof of claim 11, wherein thefirst hollow metal roof section further comprises: a first partitionwall separating the first hollow metal roof section from the secondhollow metal roof section, wherein one end of the first interconnectingcross-over drain is disposed adjacent the first partition wall.
 14. Thesplit spray-cooled roof of claim 13, wherein the second hollow metalroof section further comprises: a second partition wall facing the firstpartition wall of the first hollow metal roof section, wherein anotherend of the interconnecting cross-over drain is disposed adjacent thesecond partition wall.
 15. The split spray-cooled roof of claim 13,wherein the first hollow metal roof section further comprises: a secondpartition wall separating the first hollow metal roof section from thesecond hollow metal roof section; and a second interconnectingcross-over drain coupling to the enclosed space of the first hollowmetal roof section to the enclosed space of the second hollow metal roofsection in an orientation that allows gravitational fluid passagebetween the enclosed spaces.
 16. The split spray-cooled roof of claim13, wherein the first hollow metal roof section further comprises: aradial split line chamfers along a lowermost edge of the first partitionwall.
 17. The split spray-cooled roof of claim 11 further comprising: anevacuation drain disposed along an outer wall of each hollow metal roofsection, the evacuation drain fluidly coupled to the enclosed spaces ofthe first and second hollow metal roof sections.
 18. The splitspray-cooled roof of claim 17, wherein a first portion of the evacuationdrain is coupled to the first hollow metal roof section, and a secondportion of the evacuation drain is coupled to the second hollow metalroof section, and wherein the first and second portions are detachablycoupled by an interconnected extension.
 19. The split spray-cooled roofof claim 18 further comprising: one or more outer liquid drain openingsfluidly coupling the first portion of the evacuation drain to theenclosed space of the first hollow metal roof section; and one or moreouter liquid drain openings fluidly coupling the second portion of theevacuation drain to the enclosed space of the second hollow metal roofsection.